Nowadays, fingerprint imaging systems have been widely used in various products. Generally, an optical fingerprint imaging system includes a backlight system and a sensor array. In some solutions, a fiber-optical plate as a protective plate is formed on the sensor array to protect the sensor array and reduce light scattering. However, some lights may be emitted from gratings of the fiber-optical plate with angle deviation, which still causes light scattering and crosstalk. Therefore, the possibility of light scattering and crosstalk in an optical fingerprint imaging system needs to be reduced.